Information which is stored in computerized systems, databases or repositories can change frequently. These changes are typically made without notice being given to those with access to that information. For example, software development frequently involve s access by many persons to code stored in a central location. The various programmers can change the central code without notifying the other programmers working on that code. Another example is the Internet, where the content of a resource ("home page" or "page") can be changed and all the users with access to that resource are not notified of the changes.
Persons with access to such systems, therefore, do not know on a daily basis whether and how the information has changed since a previous examination of the information. Instead the person must spend valuable time examining the information, such as the code or resource content from the examples above, to determine if there were any modifications and what the modifications were.
Many of these systems indicate that changes have been made but do not identify the actual changes. Other systems, generically known as "diff" systems, identify the changes but only in response to the user's decision to compare two specific stored versions.
Versioning control systems exist to facilitate this examination process. These systems store multiple versions of a document from different time periods. These multiple versions can be stored in full or be partially stored so that a selected version can be generated from a previous version plus incremental information concerning the intervening versions. These version control systems serve to identify differences between versions of a document stored in a local repository. Revision Control System (RCS) format is a specific example of these generic versioning systems.